using TMPro;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.InputSystem;
using UnityEngine.UI;

namespace DepthsOfGreed.HandbookUI
{
    public sealed class HandbookController : MonoBehaviour
    {
        [SerializeField] private GameObject closedBook;
        [SerializeField] private GameObject openBook;
        [SerializeField] private Button bookButton;
        [SerializeField] private Button closeButton;
        [SerializeField] private RectTransform closedTabsRoot;
        [SerializeField] private RectTransform openTabsRoot;
        [SerializeField] private Button[] closedTabs;
        [SerializeField] private Button[] openTabs;
        [SerializeField] private GameObject[] pages;
        [SerializeField] private GameObject testTowerPrefab;
        [SerializeField] private HandbookTowerCatalog towerCatalog;
        [Tooltip("Optional: component implementing IHandbookGameplay. Empty uses the prototype backend.")]
        [SerializeField] private MonoBehaviour gameplayBackend;
        [Tooltip("Wartezeit nach erfolgreichem Platzieren, bevor das Buch hochfährt.")]
        [SerializeField, Min(0)] private float successfulPlacementDelay = 0.5f;
        [Header("Tab movement (Build, Statistics, Upgrades, Index)")]
        [Tooltip("Distance left per closed tab. -1 automatically uses its width. Rest position is the authored RectTransform position.")]
        [SerializeField] private float[] closedTabRevealDistances = { -1f, -1f, -1f, -1f };
        [Tooltip("Distance up per open tab. -1 automatically uses its height.")]
        [SerializeField] private float[] openTabRevealDistances = { -1f, -1f, -1f, -1f };
        [Tooltip("Overlap retained when an automatically sized tab is fully revealed.")]
        [SerializeField, Min(0)] private float closedTabOverlap = 10f;
        [SerializeField, Min(0)] private float openTabOverlap = 25f;
        [SerializeField] private float animationSpeed = 14f;

        private readonly string[] titles = { "Bauen", "Statistik", "Upgrades", "Index" };
        private Vector2[] closedPositions, openPositions;
        private TMP_Text[] closedLabels, openLabels;
        [SerializeField] private RectTransform activeLayer;
        private int selected, hoveredClosed = -1, hoveredOpen = -1;
        private bool isOpen, bookHovered;
        private Vector3 bookScale;
        private BuildMenuController buildMenu;
        private TestPlacementController placement;
        private HandbookIndexController indexMenu;

        private void Awake()
        {
            if (!closedBook || !openBook || !bookButton || !closeButton ||
                !openTabsRoot || !closedTabsRoot || closedTabs.Length != 4 ||
                openTabs.Length != 4 || pages.Length != 4)
            {
                Debug.LogError("Handbuch: Inspector-Verbindungen fehlen.", this);
                enabled = false;
                return;
            }
            closedPositions = PrepareTabs(closedTabs, out closedLabels, false);
            openPositions = PrepareTabs(openTabs, out openLabels, true);
            bookScale = bookButton.transform.localScale;
            bookButton.onClick.AddListener(() => Open(0));
            closeButton.onClick.AddListener(Close);
            AddHover(bookButton.gameObject, () => bookHovered = true, () => bookHovered = false);
            buildMenu = pages[0].GetComponent<BuildMenuController>();
            buildMenu.Initialize(towerCatalog);
            placement = gameObject.GetComponent<TestPlacementController>();
            placement.Initialize(this, buildMenu, (RectTransform)openBook.transform, testTowerPrefab, gameplayBackend);
            placement.SuccessfulPlacementDelay = successfulPlacementDelay;
            buildMenu.Placement = placement;
            indexMenu = pages[3].GetComponent<HandbookIndexController>();
            indexMenu.Initialize(towerCatalog);
            var upgrades = pages[2].GetComponent<HandbookUpgradesController>();
            upgrades.Initialize(placement);
            Close();
        }

        private Vector2[] PrepareTabs(Button[] tabs, out TMP_Text[] labels, bool opened)
        {
            var positions = new Vector2[tabs.Length];
            labels = new TMP_Text[tabs.Length];
            for (int i = 0; i < tabs.Length; i++)
            {
                int index = i;
                positions[i] = ((RectTransform)tabs[i].transform).anchoredPosition;
                labels[i] = tabs[i].GetComponentInChildren<TMP_Text>(true);
                if (labels[i]) labels[i].gameObject.SetActive(false);
                tabs[i].onClick.AddListener(() => Open(index));
                AddHover(tabs[i].gameObject,
                    () => { if (opened) hoveredOpen = index; else hoveredClosed = index; },
                    () => { if (opened) { if (hoveredOpen == index) hoveredOpen = -1; }
                            else if (hoveredClosed == index) hoveredClosed = -1; });
            }
            return positions;
        }

        private static void AddHover(GameObject target, UnityEngine.Events.UnityAction enter,
            UnityEngine.Events.UnityAction exit)
        {
            var trigger = target.GetComponent<EventTrigger>();
            if (!trigger) trigger = target.AddComponent<EventTrigger>();
            var entry = new EventTrigger.Entry { eventID = EventTriggerType.PointerEnter };
            entry.callback.AddListener(_ => enter());
            trigger.triggers.Add(entry);
            var leave = new EventTrigger.Entry { eventID = EventTriggerType.PointerExit };
            leave.callback.AddListener(_ => exit());
            trigger.triggers.Add(leave);
        }

        public void Open(int index)
        {
            if (index < 0 || index >= pages.Length) return;
            bool samePage = isOpen && selected == index;
            selected = index;
            isOpen = true;
            hoveredClosed = -1;
            bookHovered = false;
            closedBook.SetActive(false);
            openBook.SetActive(true);
            for (int i = 0; i < pages.Length; i++)
            {
                pages[i].SetActive(i == index);
                var rect = (RectTransform)openTabs[i].transform;
                rect.SetParent(i == selected ? activeLayer : openTabsRoot, false);
            }
            if (index == 3 && !samePage && indexMenu) indexMenu.ResetForEntry();
            if (samePage && index == 3 && indexMenu) indexMenu.ResetForEntry();
        }

        public void Close()
        {
            if (placement && placement.IsDragging) placement.Cancel();
            if (placement) placement.ResetBookPresentation();
            if (buildMenu) buildMenu.ResetForClose();
            if (indexMenu) indexMenu.ClearSelection();
            isOpen = false;
            hoveredOpen = hoveredClosed = -1;
            bookHovered = false;
            for (int i = 0; i < openTabs.Length; i++)
            {
                ((RectTransform)openTabs[i].transform).anchoredPosition = openPositions[i];
                if (openLabels[i]) openLabels[i].gameObject.SetActive(false);
            }
            openBook.SetActive(false);
            closedBook.SetActive(true);
        }

        private void Update()
        {
            if (isOpen && (!placement || !placement.ConsumedCancelThisFrame) &&
                (!placement || !placement.IsDragging) && Keyboard.current != null && Keyboard.current.escapeKey.wasPressedThisFrame)
                Close();
            float blend = 1f - Mathf.Exp(-animationSpeed * Time.unscaledDeltaTime);
            if (!isOpen)
            {
                bookButton.transform.localScale = Vector3.Lerp(bookButton.transform.localScale,
                    bookScale * (bookHovered ? 1.04f : 1f), blend);
                AnimateTabs(closedTabs, closedPositions, closedLabels, hoveredClosed, -1, blend);
            }
            else AnimateTabs(openTabs, openPositions, openLabels, hoveredOpen, selected, blend);
        }

        private void AnimateTabs(Button[] tabs, Vector2[] positions, TMP_Text[] labels,
            int hovered, int active, float blend)
        {
            for (int i = 0; i < tabs.Length; i++)
            {
                bool show = i == hovered || i == active;
                var rect = (RectTransform)tabs[i].transform;
                // Reveal the full marker while retaining a small overlap with the page.
                bool opened = tabs == openTabs;
                var distances = opened ? openTabRevealDistances : closedTabRevealDistances;
                float configured = distances != null && i < distances.Length ? distances[i] : -1f;
                float automatic = opened
                    ? Mathf.Max(0f, -positions[i].y - openTabOverlap)
                    : Mathf.Max(0f, positions[i].x - closedTabOverlap);
                float distance = configured >= 0f ? configured : automatic;
                var target = positions[i] + (show ? (opened ? Vector2.up : Vector2.left) * distance : Vector2.zero);
                rect.anchoredPosition = Vector2.Lerp(rect.anchoredPosition, target, blend);
                if (labels[i]) labels[i].gameObject.SetActive(show);
            }
        }
    }
}